R1R2 homolytic cleavage 3R1R2 ISC 1R1R2

1
1
Cage Reactions Involving Radical Pairs
Model System


(R1-R2) homolytic cleavage 3(R1R2) ISC
1(R1R2)
recombinations disproportionations
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2
The States of a Spin Correlated Radical Pair
vector model of electron spin


1(R1R2)
3(R1R2)
3
3
ISC in Triplet Radical Pairs
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4
Spin Rephasing Mechanism for ISC
spin clock (top-down view, projection in the
xy-plane)
J lt a
S
T0
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5
Timescales for ISC in Radical Pairs
T0 S
kTS (3 X 106)(?gH Ms a1 )
Spin-orbit coupling, ?g
rate, kTS Typical organic
radical, ?g 0.000-0.001 Earths H 1G
3 X 103 Hz Lab H 100,000G 3 X
108 Hz
Hyperfine coupling, a Typical organic radical, a
10-100G 3 X 107 - 3 X 108 Hz
2 mechanisms Spin Rephasing (?g) and Spin
Flipping (a)
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6
Power of Spin in Product Distribution
T0 S
kTS (3 X 106)(?gH Ms a1 )
then kTS1/2 gt kTS-1/2
Sort nuclear spin states! Polarized
(non-Boltzmann) product distribution!